Endangered seabird just inches closer to extinction in the UK overseas territory

All but one of this year’s MacGillivray prion chicks at a surveillance site have died, adding to fears that this endangered species is nearing extinction.

Invasive alien mice are the cause of death. Since surveillance began at this location in 2014, only 21 chicks have escaped from 370 monitored nests, with the remaining chick having very little chance of surviving to leave the nest this year.

A new analysis by the RSPB predicts that if the mice are not removed from Gough Island, the MacGillivray prion may be lost forever from Gough.

All but one chick from an endangered seabird died at a surveillance site this year, putting the species’ long-term future at risk. This is another devastating year for the endangered MacGillivray prions on Gough Island, an island in Britain’s overseas territory and the world’s major nesting site for seabirds in the South Atlantic.

Out of 50 monitored nests, only one chick is still alive, with invasive mice eating many of the newly hatched chicks.

Mice were accidentally introduced to Gough Island in the 19th century, most likely by sealers. The mice have since adapted to feed on a nutritious and plentiful source of food – the seabirds. These mice are now a real threat to the eight million breeding birds that inhabit Gough, including the endangered MacGillivray prion and the critically endangered Tristan albatross. Invasive rodents have been responsible for the local extinction of MacGillivray prions from two French Southern Territory islands in the Indian Ocean.

Tristan Albatross Adult, Copyright Graham Ekins, from the Surfbirds Galleries

The RSPB has been monitoring a group of these nocturnal birds nesting in caves in a cave since 2014. The survival rate in this cave is considered an indicator of how the birds all over the island are doing.

Only one chick has fled here since 2017. This is due to the fact that mice eat the chicks or parents leave the eggs because they are attacked by the mice themselves. These mice are believed to be largely responsible for the collapse of MacGillivray’s prion populations on Gough Island from about 3.5 million pairs in 1956 to 175,000 pairs in 2020.

A new paper published Monday February 15 in Animal Conservation magazine predicts that if mice stay on the island, these birds will decline 9% every year, with a 31% chance that they will they will become extinct on Gough by 2057. However, if the mice are eradicated, there is a high chance that the population will stabilize and slowly recover.

The RSPB, in partnership with Tristan da Cunha and others, is embarking on an ambitious project this year to restore the fate of millions of seabirds by eradicating every mouse on Gough Island. This project was originally scheduled to take place in 2020 but has been delayed due to the coronavirus.

Kim Stevens, RSPB Senior Field Assistant on Gough Island, said, “It’s so annoying that so many of these little chicks have died again. MacGillivray’s prions only lay one egg a year, so it’s only heartbreaking if that one egg never reaches adulthood year after year. Even the precious chick that is still alive has seven weeks before it can fly. So there is very little chance that it will make it. However, given the upcoming restoration project, I hope that we can soon turn this island back into a global paradise for sea birds and help revitalize our world. “

For more information about the project or to donate, please visit the Gough Island website.

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